A washing machine may include a cabinet defining an appearance, a tub accommodated in the cabinet, and a drum rotatably installed in the tub. The washing machine may be classified into a top loading type and a front loading type according to a method of introducing clothes into the drum. The front loading type is generally referred to as a drum-type washing machine.
Hereinafter, description will be given in detail of a drum type washing machine employing the front loading type as one example of the related art washing machine. The front loading type drum washing machine may include an opening and a door formed on a front surface of a cabinet such that the clothes can be introduced and taken out therethrough, and a tub supported by springs and a damper within the cabinet.
The tub may have a cylindrical shape with one side open, and the drum may be rotatably installed in the tub. The tub may accommodate wash water (or washing water) therein. When the drum is rotated, only a lower part of the drum may be sunk in the wash water. Also, the wash water accommodated in the bottom of the tub may be resupplied into the tub or drum for reuse by virtue of a circulation passage (flow path) and a sump disposed in the cabinet.
Meanwhile, the wash water may be sprayed into the drum through a nozzle disposed on a front end of the drum, and then supplied to a target to be washed. Here, the nozzle may be disposed on a gasket. The gasket may be mounted to peripheries of the front openings formed on the tub and the cabinet so as to prevent the wash water within the tub from being leaked into the cabinet.
The nozzle may generally be used to spray wash water into the drum from a top of the gasket. In order to evenly spray the wash water onto the target to be washed, accommodated within the drum, the nozzle may also spray the wash water along a longitudinal direction of the drum.
Wash water containing detergent may flow through a circulation passage (or a circulation flow path) which circulates between the pump disposed below the drum and the drum, and be sprayed to the target to be washed within the drum. Here, only when the detergent is evenly adsorbed and permeates into the target to be washed, the detergent may react with contaminants stuck on the target to be washed so as to improve a washing effect. That is, detergent particles well react with the contaminants stuck on the target to be washed and the washing effect is improved when the concentration of detergent in the wash water is higher or the wash water sprayed is more atomized.
First, the concentration of detergent in the wash water may not be fully increased merely by putting more detergent into the water. This is why the detergent has to be melted in the water. Also, since a time taken by washing has to be considered, it may not be preferable to spend a long time in melting the detergent.
Several technologies have been developed to increase the concentration of detergent and shorten a detergent melting time. For example, only wash water containing detergent is circulated by itself using a pump disposed in a lower portion of a washing machine before the wash water is supplied into the drum. This may allow the detergent to be quickly supplied into the water before supplying the water into the drum.
However, the detergent melting by the self circulating method requires for a large quantity of detergent to be introduced and takes a long time until completely melting the detergent.
On the other hand, the atomization of wash water may be simply achieved if the wash water is sprayed from the nozzle by high spray pressure. The spray pressure of the nozzle may increase in such a manner of reducing a cross section of a spray opening of the nozzle. However, in a general washing machine, wash water circulates along a circulation passage and may contain foreign materials and the like. Also, powder-type detergent, for example, may form a mass without being completely melted. Accordingly, when the spray opening of the nozzle is reduced in cross section in order to atomize the wash water in the general washing machine, the nozzle may be blocked due to the foreign materials or the detergent or fail to spray the wash water smoothly.
For atomizing wash water without increasing spray pressure of a nozzle, a vibrator or the like may be used. However, this method requires for an additional device and a complicated structure, which may result in an increase in fabricating costs.